I did a partial rebuild of the 1.4i (Citroën TU3JP4) in my car(new headgasket, two new cylinder sleeves, piston rings, big-end bearings, and even reseated the valves.) a while ago. Then replaced the rear axle assembly and recently swapped out the old clutch(full kit).
I there's an instruction book around I can probably fix it.
I think... I still haven't fixed the old PFAFF sewing machine I rescued at the dump.
(It just needs a thorough clean and adjusting. I have found a service manual, but then there's the time... )